Flask



FIG. 1 is a perspective view of a flask showing my new design;

FIG. 2 is a top plan view;

FIG. 3 is a side elevational view showing the side not seen in FIG. 1;

FIG. 4 is an end elevational view showing the end not seen in FIG. 1, and

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a flask, as shown. 